Abstract
Recent progress in understanding kinetics of texturing during structural phase transitions with long-range strain interactions is reviewed. We analyse systems with elastically mediated interaction which due to its anisotropy and infinite range has a pronounced effect on kinetics and textures occurring during the phase transition. As a generic example the textures (‘stripe’ and ‘tweed’ phases) due to oxygen ordering in layered high- T c cuprates (YBCO) are discussed. An atomic ordering process in cell i generates a local stress field, which is propagated elastically to a distant cell j .The effective elastic interaction J ( R ij ) at large distances can be broken into a highly anisotropic spatial part, defining a few ‘soft’ directions coinciding with the orientation of twin boundaries, and the so-called Zener interaction J z of infinite range. The spatial part of the interaction falls off oc 1/ R 3 ij in ferroelastic and oc 1/ R 5 ij in anti-ferroelastic materials, with corresponding differences of the properties of domain walls in these two cases. We analyse the origin of tweed texture usually seen when a ferroelastic material is quenched through the transition temperature T c , and under other conditions. It is argued that a dense mass of embryos of the ordered phase is present as thermodynamic fluctuations at temperatures well above T c . These fluctuations control the length and width of the tweed microdomains observed after quenching. Further coarsening of the tweed towards a stripe texture proceeds via the creation of needle domains governed by the strains around right-angled domain walls. Unusual texture formation under sudden heating is discussed.
Published Version
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